There was some work in ARM Trusted Firmware to support saving and restoring the Generic Interrupt Controller (GICv3) before and after sleep, but it seems that the plan is to have this all in the kernel now. The point of doing this is to save power during sleep. On an RK3399 system, we save about 15mW by disabling the power rail that the GIC is on.
I was looking for whether anyone had anything in progress already or for preferences on how to do this. Marc suggested using a device tree entry to indicate the need to save and restore the GIC. There is another requirement to resend MAPC commands on certain implementations of the GICv3 which could be indicated by another device tree entry. If someone does have patches, I'll be able to test and verify them on my system since we've gotten things working with the ARM Trusted Firmware patches.